A003557 -id:A003557 - cp's OEIS frontend

A323401 Lexicographically earliest sequence such that for all i, j, a(i) = a(j) => f(i) = f(j) where f(n) = [A003557(n), A323363(n)] for all other numbers, except f(n) = 0 for odd primes.

1, 2, 3, 4, 3, 5, 3, 6, 7, 8, 3, 9, 3, 10, 10, 11, 3, 12, 3, 13, 14, 15, 3, 16, 17, 18, 19, 20, 3, 21, 3, 22, 23, 24, 23, 25, 3, 26, 27, 28, 3, 29, 3, 30, 31, 32, 3, 33, 34, 35, 32, 36, 3, 37, 32, 38, 39, 40, 3, 41, 3, 42, 43, 44, 45, 46, 3, 47, 42, 46, 3, 48, 3, 49, 50, 51, 42, 52, 3, 53, 54, 55, 3, 56, 57, 58, 59, 60, 3, 61, 62, 63, 64, 65, 59, 66, 3, 67, 68, 69, 3, 70, 3

Offset: 1

Antti Karttunen, Jan 15 2019

nonn

Restricted growth sequence transform of function f, defined as f(n) = A323372(n) for all other numbers n, except f(p) = 0 for odd primes p.
For all i, j:
  A323400(i) = A323400(j) => a(i) = a(j),
  a(i) = a(j) => A322588(i) = A322588(j),
  a(i) = a(j) => A323364(i) = A323364(j).

Antti Karttunen, Table of n, a(n) for n = 1..65537

Cf. A001615, A322588, A323363, A323364, A323400,

Cf. also A323371, A323372.

up_to = 65537;
rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
DirInverse(v) = { my(u=vector(#v)); u[1] = (1/v[1]); for(n=2, #v, u[n] = -sumdiv(n, d, if(dA001615(n) = (n * sumdivmult(n, d, issquarefree(d)/d)); \\ From A001615
v323363 = DirInverse(vector(up_to,n,A001615(n)));
A323363(n) = v323363[n];
A003557(n) = { my(f=factor(n)); for(i=1, #f~, f[i, 2] = f[i, 2]-1); factorback(f); };
Aux323401(n) = if((n>2)&&isprime(n), 0, [A003557(n), A323363(n)]);
v323401 = rgs_transform(vector(up_to, n, Aux323401(n)));
A323401(n) = v323401[n];

A323404 Lexicographically earliest sequence such that for all i, j, a(i) = a(j) => f(i) = f(j) where f(n) = [A003557(n), A023900(n), A063994(n)].

Original entry on oeis.org

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 35, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 76, 92

Offset: 1

Antti Karttunen, Jan 13 2019

nonn

For all i, j: a(i) = a(j) => A247074(i) = A247074(j).

Antti Karttunen, Table of n, a(n) for n = 1..65537

Cf. A000010, A003557, A023900, A063994, A247074, A323405.

Cf. also A323373.

up_to = 65537;
rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
A003557(n) = { my(f=factor(n)); for (i=1, #f~, f[i, 2] = max(0,f[i, 2]-1)); factorback(f); };
A023900(n) = sumdivmult(n, d, d*moebius(d)); \\ From A023900
A063994(n) = { my(f=factor(n)[, 1]); prod(i=1, #f, gcd(f[i]-1, n-1)); }; \\ From A063994
Aux323404(n) = if(1,[A003557(n), A023900(n), A063994(n)]);
v323404 = rgs_transform(vector(up_to, n, Aux323404(n)));
A323404(n) = v323404[n];

A326199 Lexicographically earliest sequence such that a(i) = a(j) => f(i) = f(j), where f(n) = [A003557(n), A046523(n), A048250(n)] for all other numbers, except f(n) = 0 for odd primes.

Original entry on oeis.org

1, 2, 3, 4, 3, 5, 3, 6, 7, 8, 3, 9, 3, 10, 10, 11, 3, 12, 3, 13, 14, 15, 3, 16, 17, 18, 19, 20, 3, 21, 3, 22, 23, 24, 23, 25, 3, 26, 27, 28, 3, 29, 3, 30, 31, 32, 3, 33, 34, 35, 32, 36, 3, 37, 32, 38, 39, 40, 3, 41, 3, 42, 43, 44, 45, 46, 3, 47, 42, 46, 3, 48, 3, 49, 50, 51, 42, 52, 3, 53, 54, 55, 3, 56, 57, 58, 59, 60, 3, 61, 62, 63, 64, 65, 59, 66, 3, 67, 68, 69, 3, 70, 3

Offset: 1

Antti Karttunen, Jul 13 2019

nonn

For all i, j:
  A295300(i) = A295300(j) => a(i) = a(j),
  A305801(i) = A305801(j) => a(i) = a(j),
  a(i) = a(j) => A294877(i) = A294877(j).

Antti Karttunen, Table of n, a(n) for n = 1..65537

Cf. A003557, A046523, A048250, A294877, A295300, A305801.

Differs from A323401 for the first time at n = 382 where a(382) = 253, while A323401(382) = 140.

up_to = 65537;
rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
A003557(n) = n/factorback(factor(n)[, 1]); \\ From A003557
A046523(n) = { my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]); };  \\ From A046523
A048250(n) = if(n<1, 0, sumdiv(n, d, if(core(d)==d, d)));
A291750(n) = (1/2)*(2 + ((A003557(n)+A048250(n))^2) - A003557(n) - 3*A048250(n));
Aux326199(n) = if((n>2)&&isprime(n),0,(1/2)*(2 + ((A046523(n) + A291750(n))^2) - A046523(n) - 3*A291750(n)));
v326199 = rgs_transform(vector(up_to,n,Aux326199(n)));
A326199(n) = v326199[n];

A328830 The second prime shadow of n: a(1) = 1; for n > 1, a(n) = a(A003557(n)) * prime(A056169(n)) when A056169(n) > 0, otherwise a(n) = a(A003557(n)).

Original entry on oeis.org

1, 2, 2, 2, 2, 3, 2, 2, 2, 3, 2, 4, 2, 3, 3, 2, 2, 4, 2, 4, 3, 3, 2, 4, 2, 3, 2, 4, 2, 5, 2, 2, 3, 3, 3, 3, 2, 3, 3, 4, 2, 5, 2, 4, 4, 3, 2, 4, 2, 4, 3, 4, 2, 4, 3, 4, 3, 3, 2, 6, 2, 3, 4, 2, 3, 5, 2, 4, 3, 5, 2, 4, 2, 3, 4, 4, 3, 5, 2, 4, 2, 3, 2, 6, 3, 3, 3, 4, 2, 6, 3, 4, 3, 3, 3, 4, 2, 4, 4, 3, 2, 5, 2, 4, 5

Offset: 1

Antti Karttunen, Oct 29 2019

nonn

a(n) depends only on prime signature of n (cf. A025487).

			For n = 30 = 2 * 3 * 5, there are three unitary prime factors, while A003557(30) = 1, which terminates the recursion, thus a(30) = prime(3) = 5.
For n = 60060 = 2^2 * 3 * 5 * 7 * 11 * 13, there are 5 unitary prime factors, while in A003557(60060) = 2 there is only one, thus a(60060) = prime(5) * prime(1) = 11 * 2 = 22.
The number 1260 = 2^2*3^2*5*7 has prime exponents (2,2,1,1) so its prime shadow is prime(2)*prime(2)*prime(1)*prime(1) = 36.  Next, 36 = 2^2*3^2 has prime exponents (2,2) so its prime shadow is prime(2)*prime(2) = 9. In fact, the term a(1260) = 9 is the first appearance of 9 in the sequence. - _Gus Wiseman_, Apr 28 2022

Antti Karttunen, Table of n, a(n) for n = 1..16384
Antti Karttunen, Data supplement: n, a(n) computed for n = 1..100000
Index entries for sequences computed from exponents in factorization of n

Column 2 of A353510.
Cf. A001221, A001222, A003557, A008578, A056169, A071625, A323022.
Differs from A182860 for the first time at a(30) = 5, while A182860(30) = 4.
Cf. A182863 for the first appearances.
A005361 gives product of prime exponents.
A112798 gives prime indices, sum A056239.
A124010 gives prime signature, sorted A118914.
A181819 gives prime shadow, with an inverse A181821.
A325131 lists numbers relatively prime to their prime shadow.
A325755 lists numbers divisible by their prime shadow.
Cf. A109297, A182850, A353393, A353507.

A003557(n) = { my(f=factor(n)); for (i=1, #f~, f[i, 2] = f[i, 2]-1); factorback(f); }; \\ From A003557
A056169(n) = { my(f=factor(n)[, 2]); sum(i=1, #f, f[i]==1); }; \\ From A056169
A328830(n) = if(1==n,n, my(u=A056169(n)); if(0==u,1,prime(u)) * A328830(A003557(n)));

a(1) = 1; for n > 1, a(n) = A008578(1+A056169(n)) * a(A003557(n)).
A001221(a(n)) = A323022(n).
A001222(a(n)) = A071625(n).
a(n) = A181819(A181819(n)). - Gus Wiseman, Apr 27 2022

Added Gus Wiseman's new name to the front of the definition. - Antti Karttunen, Apr 27 2022

A347127 a(n) = A327251(n) / A003557(n).

Original entry on oeis.org

1, 5, 7, 8, 11, 35, 15, 11, 11, 55, 23, 56, 27, 75, 77, 14, 35, 55, 39, 88, 105, 115, 47, 77, 17, 135, 15, 120, 59, 385, 63, 17, 161, 175, 165, 88, 75, 195, 189, 121, 83, 525, 87, 184, 121, 235, 95, 98, 23, 85, 245, 216, 107, 75, 253, 165, 273, 295, 119, 616, 123, 315, 165, 20, 297, 805, 135, 280, 329, 825, 143, 121

Offset: 1

Antti Karttunen, Aug 23 2021

Antti Karttunen, Table of n, a(n) for n = 1..20000

Cf. A001615, A003557, A327251.

Cf. also A048250, A347128, A347129.

f[p_, e_] := (p + 1)*e + p; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Aug 24 2021 *)

A347127(n) = { my(f=factor(n)); prod(i=1, #f~, ((f[i, 1]+1)*f[i, 2] + f[i, 1])); };

A001615(n) = if(1==n,n, my(f=factor(n)); prod(i=1, #f~, f[i, 1]^f[i, 2] + f[i, 1]^(f[i, 2]-1))); \\ After code in A001615
A003557(n) = (n/factorback(factorint(n)[, 1]));
A327251(n) = sumdiv(n, d, A001615(n/d)*d);
A347127(n) = (A327251(n) / A003557(n));

Multiplicative with a(p^e) = ((p+1)*e + p) for prime p.

a(n) = A327251(n) / A003557(n).

A347963 Dirichlet convolution of A342001 with A003557.

Original entry on oeis.org

0, 1, 1, 3, 1, 7, 1, 7, 3, 9, 1, 18, 1, 11, 10, 15, 1, 18, 1, 24, 12, 15, 1, 40, 3, 17, 8, 30, 1, 54, 1, 31, 16, 21, 14, 45, 1, 23, 18, 54, 1, 68, 1, 42, 27, 27, 1, 84, 3, 24, 22, 48, 1, 48, 18, 68, 24, 33, 1, 132, 1, 35, 33, 63, 20, 96, 1, 60, 28, 90, 1, 99, 1, 41, 27, 66, 20, 110, 1, 114, 22, 45, 1, 168, 24, 47

Offset: 1

Antti Karttunen, Sep 24 2021

nonn

Antti Karttunen, Table of n, a(n) for n = 1..16384

Cf. A003415, A003557, A342001.

Cf. also A347961.

A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
A003557(n) = (n/factorback(factorint(n)[, 1]));
A342001(n) = (A003415(n) / A003557(n));
A347963(n) = sumdiv(n,d,A003557(n/d)*A342001(d));

a(n) = Sum_{d|n} A003557(d) * A342001(n/d).

A348498 a(n) = gcd(A003415(n), A347130(n)) / A003557(n), where A003415 is the arithmetic derivative and A347130 is its Dirichlet convolution with the identity function.

Original entry on oeis.org

0, 1, 1, 1, 1, 5, 1, 3, 1, 7, 1, 8, 1, 9, 8, 2, 1, 7, 1, 12, 10, 13, 1, 11, 1, 15, 3, 16, 1, 31, 1, 5, 14, 19, 12, 5, 1, 21, 16, 17, 1, 41, 1, 24, 13, 25, 1, 14, 1, 9, 20, 28, 1, 9, 16, 23, 22, 31, 1, 46, 1, 33, 17, 3, 18, 61, 1, 36, 26, 59, 1, 13, 1, 39, 11, 40, 18, 71, 1, 22, 2, 43, 1, 62, 22, 45, 32, 35, 1, 41

Offset: 1

Antti Karttunen, Oct 23 2021

nonn

Antti Karttunen, Table of n, a(n) for n = 1..20000

Cf. A003415, A003557, A342001, A347129, A347130, A348497, A348502 [= a(A276086(n))].

Cf. also A348494, A348496.

f[n_] := If[n < 2, 0, n Total[#2/#1 & @@@ FactorInteger[n]]]; Table[GCD[f[n], DivisorSum[n, # f[n/#] &]]*Apply[Times, FactorInteger[n][[All, 1]]]/n, {n, 90}] (* Michael De Vlieger, Oct 25 2021 *)

A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
A003557(n) = (n/factorback(factorint(n)[, 1]));
A347130(n) = sumdiv(n,d,d*A003415(n/d));
A348498(n) = (gcd(A003415(n), A347130(n))/A003557(n));

a(n) = A348497(n) / A003557(n).

a(n) = gcd(A342001(n), A347129(n)).

A348501 a(n) = A348496(A276086(n)), where A348496(n) = A348495(n) / A003557(n).

Original entry on oeis.org

1, 1, 1, 5, 1, 21, 1, 1, 1, 1, 3, 3, 1, 3, 1, 3, 1, 3, 1, 1, 1, 1, 1, 3, 1, 1, 5, 35, 3, 3, 1, 3, 5, 1, 1, 3, 3, 1, 1, 13, 3, 3, 1, 3, 1, 3, 1, 3, 13, 3, 1, 1, 1, 3, 3, 1, 5, 5, 39, 3, 1, 3, 1, 3, 1, 3, 3, 9, 3, 3, 9, 9, 1, 3, 1, 3, 1, 3, 1, 3, 1, 57, 1, 3, 57, 9, 15, 15, 3, 9, 1, 1, 1, 1, 1, 3, 1, 1, 1, 1, 3, 3

Offset: 0

Antti Karttunen, Oct 21 2021

Antti Karttunen, Table of n, a(n) for n = 0..11550
Index entries for sequences related to primorial base

Cf. A003557, A276086, A348495, A348496.

Cf. also A348500, A348502.

Block[{b = MixedRadix[Reverse@ Prime@ Range@ 12]}, Map[Function[n, GCD[Total@ GCD[n, Range[n]], DivisorSum[n, #*(If[# < 2, 0, # Total[#2/#1 & @@@ FactorInteger[#]]] &[n/#]) &]]/Apply[Times, Map[#1^(#2 - 1) & @@ # &, FactorInteger[n]]]], Table[Function[k, Times @@ Power @@@ # &@ Transpose@ {Prime@ Range@ Length@ k, Reverse@ k}]@ IntegerDigits[n, b], {n, 0, 101}] ] ] (* Michael De Vlieger, Oct 21 2021 *)

\\ Needs also code from A348496:
A276086(n) = { my(m=1, p=2); while(n, m *= (p^(n%p)); n = n\p; p = nextprime(1+p)); (m); };
A348501(n) = A348496(A276086(n));

a(n) = A348496(A276086(n)).

A349612 Dirichlet convolution of A342001 [{arithmetic derivative of n}/A003557(n)] with A325126 [Dirichlet inverse of rad(n)].

Original entry on oeis.org

0, 1, 1, 0, 1, 0, 1, 1, -1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, -3, 0, 3, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 1, 0, -5, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, -5, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0

Offset: 1

Antti Karttunen, Nov 23 2021

sign

Antti Karttunen, Table of n, a(n) for n = 1..20000

Cf. A003415, A003557, A007947, A342001, A325126.

Cf. also A349394, A349396, A349618.

f[p_, e_] := e/p; d[1] = 0; d[n_] := n * Plus @@ f @@@ FactorInteger[n]; f1[p_, e_] := p^(e-1); s1[1] = 1; s1[n_] := Times @@ f1 @@@ FactorInteger[n]; f2[p_, e_] := -p*(1 - p)^(e - 1); s2[1] = 1; s2[n_] := Times @@ f2 @@@ FactorInteger[n]; a[n_] := DivisorSum[n, d[#]*s2[n/#]/s1[#] &]; Array[a, 100] (* Amiram Eldar, Nov 23 2021 *)

A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
A003557(n) = (n/factorback(factorint(n)[, 1]));
A342001(n) = (A003415(n) / A003557(n));
A007947(n) = factorback(factorint(n)[, 1]); \\ From A007947
memoA325126 = Map();
A325126(n) = if(1==n,1,my(v); if(mapisdefined(memoA325126,n,&v), v, v = -sumdiv(n,d,if(dA007947(n/d)*A325126(d),0)); mapput(memoA325126,n,v); (v)));
A349612(n) = sumdiv(n,d,A342001(d)*A325126(n/d));

a(n) = Sum_{d|n} A342001(d) * A325126(n/d).
If p prime, a(p) = 1. - Bernard Schott, Nov 28 2021
Dirichlet g.f.: Sum_{p prime} p^s/((p^s-1)*(p^s+p-1)). - Sebastian Karlsson, May 05 2022

A353521 Lexicographically earliest infinite sequence such that a(i) = a(j) => A003415(i) = A003415(j), A003557(i) = A003557(j) and A000035(i) = A000035(j), for all i, j >= 1.

Original entry on oeis.org

1, 2, 3, 4, 3, 5, 3, 6, 7, 8, 3, 9, 3, 10, 11, 12, 3, 13, 3, 14, 15, 16, 3, 17, 18, 19, 20, 21, 3, 22, 3, 23, 24, 25, 26, 27, 3, 28, 29, 30, 3, 31, 3, 32, 33, 34, 3, 35, 36, 37, 38, 39, 3, 40, 29, 41, 42, 22, 3, 43, 3, 44, 45, 46, 47, 48, 3, 49, 50, 51, 3, 52, 3, 53, 54, 55, 47, 56, 3, 57, 58, 59, 3, 60, 42, 61, 62, 63, 3, 64, 38

Offset: 1

Antti Karttunen, Apr 27 2022

nonn

Restricted growth sequence transform of the triplet [A003415(n), A003557(n), A000035(n)].
For all i, j:
  A305801(i) = A305801(j) => A353520(i) = A353520(j) => a(i) = a(j),
  a(i) = a(j) => A007814(i) = A007814(j),
  a(i) = a(j) => A344025(i) = A344025(j),
  a(i) = a(j) => A353522(i) = A353522(j).

Antti Karttunen, Table of n, a(n) for n = 1..65537

Cf. A000035, A003415, A003557, A007814.

Cf. also A305801, A344025, A351260, A353520, A353522.

up_to = 65537;
rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
A000035(n) = (n%2);
A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));
A003557(n) = (n/factorback(factorint(n)[, 1]));
Aux353521(n) = [A003415(n), A003557(n), A000035(n)];
v353521 = rgs_transform(vector(up_to,n,Aux353521(n)));
A353521(n) = v353521[n];

cp's OEIS Frontend

A323401 Lexicographically earliest sequence such that for all i, j, a(i) = a(j) => f(i) = f(j) where f(n) = [A003557(n), A323363(n)] for all other numbers, except f(n) = 0 for odd primes.

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A323404 Lexicographically earliest sequence such that for all i, j, a(i) = a(j) => f(i) = f(j) where f(n) = [A003557(n), A023900(n), A063994(n)].

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A326199 Lexicographically earliest sequence such that a(i) = a(j) => f(i) = f(j), where f(n) = [A003557(n), A046523(n), A048250(n)] for all other numbers, except f(n) = 0 for odd primes.

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A328830 The second prime shadow of n: a(1) = 1; for n > 1, a(n) = a(A003557(n)) * prime(A056169(n)) when A056169(n) > 0, otherwise a(n) = a(A003557(n)).

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A347127 a(n) = A327251(n) / A003557(n).

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A347963 Dirichlet convolution of A342001 with A003557.

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A348498 a(n) = gcd(A003415(n), A347130(n)) / A003557(n), where A003415 is the arithmetic derivative and A347130 is its Dirichlet convolution with the identity function.

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A348501 a(n) = A348496(A276086(n)), where A348496(n) = A348495(n) / A003557(n).

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